George m



(No Model.) 2 sheets-sheet 1. G. M. SBARLE & G. N. SABGMULLBR.

RANGE FINDER.

Patented Aug. 10, 1897.

A TTUR/VEYS.

(No Model.) 2 Sheets-SheetZ G. M. SEARLE 8v G. N. SABGMULLER.

RANGE FINDER.

No. 588,093.l Patented Aug. 10, 1897.

INVENTHS.'

Arm/Mfrs.

.UNITED STATES PATENT OFFICE. i

GEORGE M. SEARLE AND GEORGE N. SAEGMULLER, OF W'ASHINGTON, DISTRICT OF COLUMBIA.

RANGE-FINDER.l

SPECIFICATION forming part of Letters Patent No. 588,093, dated August 10, 1897'.

Application led April 12, 1897. Serial No. 631,755. (No model.)

To all whom it may concern.-

Be it known that we, GEORGE M. SEARLE and GEORGE N. SAEGMULLERpf Washington, in the District of Columbia, have invented a new and useful Improvement inRange-Finders, of which the following is a specification.

The object of our invention is to provide a range-iinder for determining thedistance of remote objects, such as an enemys vessel at sea, which shall in a practical and convenient manner by a simple adjustment indicate at once without calculation the distance of such remote object upon a scale on the instrument.

It consists in the instrument hereinafter shown and described, reference being had to the accompanying drawings, in which- Figure l` is a front elevation of the instrument, taken from the sidefacing the remote object. Fig. 2 is a rear elevation taken from the side facing the observer. Fig. 3 is a plan or top view. Fig. 4 is a diagram illustrating the principles of the constant angle upon which our instrument is based. Fig. 5 is an enlarged section through line 5 5, Fig. 3. Fig. G is a similar section through line 6 6, Fig. 5; and Figs. 7 and 8 are details of modifications.

In the drawings, A represents any pedestal, pillar, or upright support, which at its upper end bears a cross-arm B, about ten feet long, extending on both sides of the` pedestal and pivoted thereon to turn about a vertical axis. This arm occupies the position of the base of the triangle shown in Fig. 4 from l to 5,000. It will be understood that the actual triangle made by the remote object with the two ends of the base of the instrument will be very attenuated, and the angle at so, Fig. 4, will be very much smaller than shown on this diagram, which is only used for purposes of illustration, our invention being founded upon the following facts: That if a base-line of 5,000 has a prism at 5,000 adj usted to catch and send into a telescope the image of the object at a distance of five thousand yards, then if the prism of the base-line be moved toward the left whenever the prism catches the ray from an object at y, exactly half the distance, or two thousand live hundred yards, then the adjust-able prism will mark on the scale of the base-line the indication 2500, on the principle of the constant angle.

Upon the extremities of the cross-arm B are mounted bearings b b, in which turn the trunnions c c of a horizontal base-line bar O,which is graduated on the side next the observer in aliquot markings of from one to five thousand yards, or whatever is to be the limit of the range-finder. On this base -line bar C is mounted a sliding carriage E, having an oir"- setting plate c on its front side, (see Fig. 3,) which carries a prism D', which is adapted to receive the incident ray and send out the emergent ray at right angles to each other. For this purpose we prefer the double reiiect ing-prism shown,bu t a single right-angular 1'e iiecting prism or mirror might be used. As be fore said, however, we prefer the double re lecting-prism,because slight variations in the positions of this prism do not affect the proper alinement of the emergent ray. At the'other end of Ithe base-line bar C is another prism D, o the same construction; but these two prisms are not in the same` horizontal plane, but the bottom of the outer one D is on a level with the top of the inner one D, as seen in Fig. l, so that independent images received in the direction of the arrows in Fig. 3 will be projected onto the reflecting-prism F, (or mirron) and be thence reflected at right angles to the base-line into the telescope G, which stands at right angles to the base-line bar O. 1

The prism D, supporting-plate d, right-angular reflecting-prism F, (or mirror,) and telescope G are all fixed in stationary relation upon one end of the base-line bar, and by virtue of the vertical pivot on the pedestal and the horizontal trunnions c c may be moved to any desired position either verticallyor horizontally.

To adjust the movable prism D' along the base-line, its slidingcarriage E is attached to an endless chain Il, which passes around small sprocket-wheels 71, 72, at the end ofthe base-line bar C and on the 'side next to the observer, the sliding carriage being provided with a pointer p, playing over the graduated scale c2. One of these wheels, h, is provided with an axial stem and hand-wheel h2, by which it may be turned to give motion' to the chain and adjust the carriage E and its prism D to any position along the base-line bar.

IOO

The method of adjusting and using the instrument is as follows: lf the prisms D and D are at opposite ends of the base-line (bar C) and one is above and the other below or occupying adjacent but different horizontal planes, it is obvious that the image of a remote object entering prism D and being reflected by prism F (or mirror) will appear at one point on one half of the object-glass of the telescope G, while the image of the other prism D, reliected by prism F, (or mirror,) will appear at another point on the ot-her half of the object-glass, and two images will thus appear separated a greater or less distance, according to the distance between the prisms D D' or the length of the base-line as compared with the distance of the object viewed. Now these two images we bring into coincidence for an obj ect a predetermined distance away, which shall be the limit of the rangender-say five thousand yards. To do this, we place a refracting glass plate in the telescope in the path of the rays from one of the prisms, the refractive iniiuence of which plate on these rays of one prism shall throw them into direct and exact coincidence with the rays of the other prism, so that but one image will appear. This coincidence being fixed for the predetermined distance-.say five thousand yards-as at x, Fig. 4, it will be seen that if it is sought to find the unknown distance. of an object at y the telescope when directed thereat will show two images until the prism D' is adjustedV to the position on the scale which marks the distance of that object, and when such object appears as a single image then the position of the prism D will mark on its scale the actual distance of the object sought, or two thousand ve hundred yards, on the principle of the constant angle, as illustrated in the diagram. The position and means for adjusting this glass plate are seen in Fig. 5, where one half of the object appears through the object-glass only, while the other half appears through the refracting glass plate w. This plate is pivotally mounted and provided with an adjusting-stem and jam-nut, and being adj ust-ed once for all to bring the images into coincidence at a predetermined distance must not be changed or tampered with, and for this reason its adjusting-nut is housed within an inclosing cap.

As a modification of our invention wel may dispense with the large reflecting-prism F, Fig. 3, which is very expensive, and place the telescope G in alinement with the base-line, as indicated by dotted lines in Fig. 3. In such case the telescope has the same refracting-plate fw, (see Fig. 7,) and the eyepiece is at right angles to the telescope, and a small right-angular reIiecting-prism tis placed at the angle of the eyepiece and the telescope G', as shown in Fig. 7.

As a further modiication we may do away entirely with the refracting-plate of glass in the telescope for bringing the two images into coincidence and accomplish this result by dividing diametrically the object-glass itself, as seen in Fig. 8, and moving one half'of the object-glass so as take the two images on the two halves of the object-glass and adjust one of these halves according to a predetermined distance, so as to bring the two images into coincidence on the same principle.

The fundamental principles involved in this case are similar to those in another application for a patent filed by us of even date herewith, Serial No. 631,756, and marked Case B, the only difference being that in the present case the readings on the scale are marked by the adjustment of one of the prisms, the position and form of the refracting (or coincidence) plate remaining constant, while in.

said other case the two prisms are iixed and the readings are taken by the radial adjustment of the refracting (or coincidencelplate by means of a pointer on a cotangent scale.

Having thus described our invention, what we claim as new, and desire to secure by Let! base-line bar bearing a fixed rightlangular-reV fleeting surface, an adj ustable Vrigh,i3-angularrefiecting surface movable along the base-line bar, said reflecting-surfaces being arranged to receive the incident rays and send out the emergent rays in different parallel planes info a telescope, a telescope adapted to receiveon its object-glass the two sets of ray`s,eand a refracting-plate arranged within said telescope to receive the one set of rays from oney of said'reiiecting-surfaces and deflect their image into coincidence with that of the other set of rays from the other reflecting-'surface substantially as and for the purpose described.

IIO

3. A range-iinder comprising a telescope constructed to bring two images into coincidence, a graduated base-line bar mounted upon axes at right angles to each oth er,and

carrying at one end a fixed right-angularlyreflecting prism, a movable carriage sliding on the base-line bar and bearing a right-anand adjusting-handle for operating said chain j Aand adjusting the carriage with movable reflecting-surface along the base-line bar, "sru'bstantially asa'nd'for the purpose described.`

4. A range-finder comprising a graduatedA base-line barv having at one'end a fixed rightangular reflecting surface, an adjustable reflecting-surface forbrnging the line ofsight' Io right angular reflecting surface movable at right angles to the base-line bar substanalong the base-line bar, said surfaces being tially as and for the purpose described.

arranged in diierent planes to send their re- 5 speotive emergent rays to a different portion of the object-glass of a telescope, a telescope mounted near the stationary reiecting-sur- Witnesses: face of the base-line bar, and having a re- EDW. W. BYRN,

fraoting-plate as described, and an additional SOLON C. KEMON. 

